Improve performance let-binding `case-fold-search' (bug#66117)

* src/buffer.h: Remove case_fold_search_ buffer object slot.
* src/buffer.c (bset_case_fold_search): Remove - no longer needed.
(init_buffer_once): Remove removed buffer slot init.
(syms_of_buffer): Use DEFVAR_LISP to define `case-fold-search' and
declare it buffer-local.
* src/minibuf.c (syms_of_minibuf): Remove DEFSYM call for
`case-fold-search' symbol.  It now lives in `syms_of_buffer'.
* src/editfns.c (Fcompare_buffer_substrings):
(Fchar_equal):
* src/search.c (looking_at_1):
(string_match_1):
(search_command):
(Fre__describe_compiled): Adjust C queries to `case-fold-search' value
to use C globals instead of BVAR macro.
* doc/lispref/internals.texi (Buffer Internals): Do not list
`case_fold_search' slot.

See https://debbugs.gnu.org/cgi/bugreport.cgi?bug=66117#259

When used as buffer slot, let-binding `case-fold-search' would scale
with the number of live buffers and can be slow.  This change makes
let-binding much faster at the cost of slightly slower `set-buffer'.

1 files changed, 6 insertions, 11 deletions

diff --git a/src/buffer.c b/src/buffer.c
index d08ea44d797..637830704e6 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -210,11 +210,6 @@ bset_buffer_file_coding_system (struct buffer *b, Lisp_Object val)
   b->buffer_file_coding_system_ = val;
 }
 static void
-bset_case_fold_search (struct buffer *b, Lisp_Object val)
-{
-  b->case_fold_search_ = val;
-}
-static void
 bset_ctl_arrow (struct buffer *b, Lisp_Object val)
 {
   b->ctl_arrow_ = val;
@@ -4692,7 +4687,6 @@ init_buffer_once (void)
   XSETFASTINT (BVAR (&buffer_local_flags, mode_line_format), idx); ++idx;
   XSETFASTINT (BVAR (&buffer_local_flags, abbrev_mode), idx); ++idx;
   XSETFASTINT (BVAR (&buffer_local_flags, overwrite_mode), idx); ++idx;
-  XSETFASTINT (BVAR (&buffer_local_flags, case_fold_search), idx); ++idx;
   XSETFASTINT (BVAR (&buffer_local_flags, auto_fill_function), idx); ++idx;
   XSETFASTINT (BVAR (&buffer_local_flags, selective_display), idx); ++idx;
   XSETFASTINT (BVAR (&buffer_local_flags, selective_display_ellipses), idx); ++idx;
@@ -4785,7 +4779,6 @@ init_buffer_once (void)
   bset_tab_line_format (&buffer_defaults, Qnil);
   bset_abbrev_mode (&buffer_defaults, Qnil);
   bset_overwrite_mode (&buffer_defaults, Qnil);
-  bset_case_fold_search (&buffer_defaults, Qt);
   bset_auto_fill_function (&buffer_defaults, Qnil);
   bset_selective_display (&buffer_defaults, Qnil);
   bset_selective_display_ellipses (&buffer_defaults, Qt);
@@ -5215,10 +5208,6 @@ Format with `format-mode-line' to produce a string value.  */);
                      doc: /*  Non-nil if Abbrev mode is enabled.
 Use the command `abbrev-mode' to change this variable.  */);
 
-  DEFVAR_PER_BUFFER ("case-fold-search", &BVAR (current_buffer, case_fold_search),
-                     Qnil,
-                     doc: /* Non-nil if searches and matches should ignore case.  */);
-
   DEFVAR_PER_BUFFER ("fill-column", &BVAR (current_buffer, fill_column),
                      Qintegerp,
                      doc: /* Column beyond which automatic line-wrapping should happen.
@@ -5951,6 +5940,12 @@ If `delete-auto-save-files' is nil, any autosave deletion is inhibited.  */);
 This is the default.  If nil, auto-save file deletion is inhibited.  */);
   delete_auto_save_files = 1;
 
+  DEFVAR_LISP ("case-fold-search", Vcase_fold_search,
+               doc: /* Non-nil if searches and matches should ignore case.  */);
+  Vcase_fold_search = Qt;
+  DEFSYM (Qcase_fold_search, "case-fold-search");
+  Fmake_variable_buffer_local (Qcase_fold_search);
+
   DEFVAR_LISP ("clone-indirect-buffer-hook", Vclone_indirect_buffer_hook,
                doc: /* Normal hook to run in the new buffer at the end of `make-indirect-buffer'.